overfuelling

[:madaz:]

we all know what leaning out can do to a (especially) turbo car but on the other side of the scale, how major damage can be done by running far to rich?? is it possible to melt pistons running rich?? what other bad symptoms does a rich running engine gain if not tuned ??

[Ae92typeX]

bore wash...its just as bad in the end (just in different ways)...still means a rebuild.

[Si]

As far as i remember anything below about (there are lots of variables here) 8:1 air fuel will cause the borewash issue

If you cant afford tuning then be aware that your burning more fuel than you probably need to, therefore its costing you money

[jondee86]

It's amazing what you can find on the internet. This for example....

A FULLY WARMED UP ENGINE WITH AN A/F RATIO AS RICH AS
6.0-1 AND AS LEAN AS 22.0-1, THESE ARE THE GENERAL RICH AND LEAN
COMBUSTION LIMITS, BUT DURING ACTUAL DRIVING SITUATIONS THE
ACTUAL A/F RATIO NEEDED DURING VARIOUS OPERATING CONDITIONS
WILL BE VERY CLOSE TO THE MID-POINT OF THESE EXTREMES.

A/F RATIO / COMMENT

9.0:1 BLACK SMOKE (NO POWER)

11.5:1 RICH BEST TORQUE @ WOT

12.2:1 SAFE BEST POWER @ WOT

13.3:1 LEAN BEST TORQUE @ WOT

14.6:1 STOCHIMETRIC AFR ( CHEMICALLY CORRECT )

15.5:1 LEAN CRUISE

16.5:1 BEST FUEL ECONOMY (EXCEPT FOR HONDA)

18.0:1 CARBURETED LEAN LIMIT (EXCEPT FOR HONDA)

22.0:1 EFI LEAN LIMIT

GENERALLY ENGINES OF DIFFERENT BASIC DESIGNS HAVE THE SAME
A/F RATIO REQUIREMENTS. THESE CALIBRATION NEEDS ARE TYPICALLY
A FUNCTION OF OPERATION MODE, ENGINE TEMPERATURE, ENGINE
SPEED, AND LOAD. GENERALLY A PRODUCTION BASED HIGH
PERFORMANCE ENGINE WILL HAVE A/F RATIO VALUES IN A RANGE FROM
12.0:1 TO 16.0:1.

This info is stolen from a Toyota high performance site, so I don't know
about the Honda comments. Maybe Honda have better lean burn
technology ??

Cheers.... jondee86